1. Field of the Invention
The present invention relates to a semiconductor memory device, and, more particularly, to a semiconductor memory device having an open bitline structure.
2. Description of the Related Art
Conventionally, semiconductor memory devices have been designed using a folded bitline structure. In the folded bitline structure, a bitline and a complementary bitline are both disposed in the same memory-cell array region, which causes the same amount of coupling noise between the bitline and a wordline as that generated between the complementary bitline and the wordline. This type of common mode noise can be easily removed by performing differential amplification using a sense amplifier. However, since there is a limit in reducing the size of memory cells using the folded bitline structure, research is being conducted on an open bitline structure in an effort to increase the integration density of semiconductor memory devices.